Atraumatic osteonecrosis of the talus.

Thirty-seven ankles in twenty-four patients were treated at our institution between July 1, 1974, and December 31, 1996, for atraumatic osteonecrosis of the talus. This group represents 2 per cent of the 1056 patients who were managed for osteonecrosis during this period. There were twenty-one women and three men, and their mean age was forty years (range, twenty-six to sixty-two years) at the time of the diagnosis. Thirteen (54 per cent) of the twenty-four patients had bilateral involvement. Sixteen patients (67 per cent) had a disease that affects the immune system, including systemic lupus erythematosus (thirteen patients), scleroderma (one), insulin-dependent diabetes mellitus (one), and multiple sclerosis (one). Four patients had a history of regular alcohol use, and four patients had a history of moderate smoking. One patient had a protein-S deficiency, one patient had had a renal transplant, and one patient had a history of asthma. Two patients had no identifiable risk factors for osteonecrosis [corrected]. Fifteen patients (63 per cent) had involvement of other large joints. The mean duration of symptoms before the patients were seen was 5.4 months (range, two months to two years). The mean ankle score at the time of presentation was 34 points (range, 2 to 75 points), according to the system of Mazur et al. A radiographic review revealed that, according to the system of Ficat and Arlet, eight ankles had stage-III or IV disease of the talus at presentation. The remaining twenty-nine ankles had stage-II disease. The osteonecrosis was seen in the posterolateral aspect of the talar dome (zones III and IV on the sagittal images and zones II, III, and IV on the coronal images) in twenty-two of the twenty-three ankles for which magnetic resonance images were available. The osteonecrosis was seen in the anteromedial aspect of the talar dome (zones I and II on the sagittal images and zone I on the coronal images) in the remaining ankle. Bone scans, which were available for eleven ankles, revealed increased uptake in the talus. All patients were initially managed non-operatively with restricted weight-bearing, an ankle-foot orthosis, and use of analgesics; two ankles responded to this regimen. Thirty-two ankles that remained severely symptomatic were treated with core decompression, which was useful in the treatment of precollapse (stage-II) disease. Twenty-nine of these ankles had a fair-to-excellent clinical outcome a mean of seven years (range, two to fifteen years) postoperatively; the remaining three ankles had an arthrodesis after the core decompression failed. Three ankles were treated initially with an arthrodesis for postcollapse (stage-III or IV) disease. All six of the ankles that had an arthrodesis fused, at a mean of seven months (range, five to nine months) postoperatively. When patients who have a history of osteonecrosis are seen because of pain in the ankle, the diagnosis of osteonecrosis of the talus should be considered. Early detection may allow the ankle to be treated non-operatively or with core decompression and thus reduce the need for arthrodesis. We also believe that when a patient has osteonecrosis of the talus, the hips should be screened with use of standard radiography or magnetic resonance imaging, or both.

The aquatic vertebrate embryo as a sentinel for toxins: zebrafish embryo dechorionation and perivitelline space microinjection.

Pollution of aquatic ecosystems poses a serious threat to aquatic organisms and ultimately the entire ecosystem. Understanding how a toxin affects embryonic development is key to determining the risk a pollutant represents to the environment. Extraembryonic membranes, such as the chorion of fish eggs, provide a protective barrier between the embryo and the environment. Although the fish chorion excludes many chemical pollutants, some noxious agents can still gain access to the aquatic embryo. Therefore a monitoring system that tests the effects directly upon the embryo must be established. Although exposure to a single toxin in the laboratory can determine the concentration at which a pollutant becomes a health or environmental hazard, embryos and adults in nature are not merely affected by a single chemical, but are exposed to mixtures of different pollutants. Zebrafish (Danio rerio) and medaka (Oryzias latipes) embryos were employed for the rapid observation of the effects of single chemicals and chemical mixtures on development. Using dechorionation and a perivitelline space microinjection system, the embryos were effective sentinels for low concentrations of aquatic pollutants. The developmental effects of small quantities of toxins were observed. Embryos treated during the late gastrula stage of development with hexachlorobenzene (HCB); 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD); toluene; benzene; or mixtures of these chemicals developed cardiovascular abnormalities. The zebrafish dechorionation exposure technique, Micro Intrachorionic Zebrafish Embryo Live Laboratory test, was especially effective in testing the pollutant mixtures. Combinations of both TCDD and benzene (as well as the toluene and benzene combinations) were tested and the mixtures acted synergistically; the combinations were more toxic than either chemical by itself. Hexachlorobenzene- and TCDD-treated embryos tested positively for expression of cytochrome P450 1A indicating that the cytochrome metabolic pathways were already functional in these early embryos, and suggested that a product of the cytochrome system may be involved in HCB and TCDD pollution associated cardiovascular defects.

Dermal sensitization potential and inhalation toxicological evaluation of 4-phenylcyclohexene.

4-Phenylcyclohexene (4-PCH) is a by-product formed in trace amounts during the production of styrene-butadiene latexes, which are used in carpet manufacturing. The dermal sensitization potential of 4-PCH was evaluated by using a modification of the Buehler method. The condition of the test site was evaluated 24 and 48 hr after the challenge application with no response observed in any of the guinea pigs. For the acute inhalation study, groups of five Fischer 344 rats/sex were exposed to 16 or 60 ppm 4-PCH for a single 6-hr exposure. Subsequently, groups of 10 Fischer 344 rats/sex were exposed to time-weighted average concentrations of 0, 1, 10, or 50 ppm (0, 6.6, 65, or 320 mg/m3) 4-PCH for 6 hr/day, 5 days/week for nine exposures. The highest vapor concentration, 50 ppm, was the maximum attainable during the course of the 2-week study. It was only achieved by acclimating the chamber with saturated vapor prior to each animal exposure. The following parameters were evaluated for the 2-week study: clinical signs, body weights, selected organ weights, hematology, clinical chemistry, urinalysis, and histopathology. All rats survived to the termination of the study and had no clinical or pathologic evidence of eye, skin, nasal, or respiratory tract irritation. There were no exposure-related effects identified in any of the parameters monitored. Thus, 4-PCH produced no toxicity at the highest concentration that could be generated and did not produce delayed contact hypersensitivity in guinea pigs.

Detection of Lucké herpes virus antigens in infected frog pronephric cells.

A frog pronephric cell line, infected with herpes virus derived from Lucké renal carcinomas of Rana pipiens was examined for the presence of Lucké herpes virus antigens. Non-infected pronephric cells were controls. Antiserum to purified Lucké tumor herpes virus was applied in blind tests to the normal and virus infected cells. Both cytoplasmic and nuclear fluorescence was found in the herpes virus infected cells after indirect immunofluorescence with the antiserum. Infected cells cultivated at the optimum growth temperature of 25 degrees C or maintained at 9 degrees C, a temperature inducive to herpes virus replication, showed equivalent fluorescence reactions. No fluorescence was found in the normal pronephric cell line. Examination of parallel herpes infected cells showed cytopathic effect in monolayers by light microscopy, and nuclear or cytoplasmic immunofluorescence. Electron microscopic examination revealed proviral elements in nuclei and sparsely scattered herpes virus coincident with cytoplasmic fluorescence.

Growth of opossum embryos in vitro during organogenesis.

Opossum embryos, explanted between primitive streak and late fetal stages, were grown in culture for periods of 20-30 H. Many of the explants had a good heartbeat and blood circulation in embryo and yolk sac after 12 h, and a few after 24 h. Growth of the embryos included formation of the neural tube and body flexures, increase in the number of somites, differentiation of the limbs and digits, and development of the amnion and allantois. Embryos explanted during the last day of gestation showed persistent and vigorous body movements in culture, particularly of the forelimbs, head and tongue.

Uremic autonomic neuropathy: evaluation of ephedrine sulphate therapy for hemodialysis-induced hypotension.

The hemodynamic response to ephedrine sulphate were studied in a patient on maintenance hemodialysis therapy with chronic renal failure due to renal amyloidosis. The evaluation (including cardiac catheterization studies) and estimation of responses to Valsalva maneuvers before and after ephedrine administration documented the diagnosis of autonomic insufficiency. Oral ephedrine failed to influence the episodes of severe dialysis-induced hypotension. Also the patient did not benefit from the infusion of Aramine. These studies suggest that catecholamine stores of adrenergic nerves may be depleted in uremic patients with clinical signs of autonomic neuropathy.

Virus-free adenocarcinoma of the frog (summer phase tumor) transcribes Lucké tumor herpesvirus-specific RNA.

[(3)H]RNA isolated from "virus-free," summer phase, renal adenocarcinomas of Rana pipiens labeled with [(3)H]uridine hybridizes with DNA of herpesvirus particles isolated from the winter phase Lucké tumor. Transcription of the herpesvirus genome in virus-free tumors provides additional evidence for the viral etiology of this tumor.

Opossum fetuses grown in culture.

Opossum fetuses explanted at limb bud stages have been successfully grown in culture for periods up to 20 hours. Blood circulation was maintained, and organogenesis continued at about the same rate as in vivo.

In vitro induction of a herpes-type virus in "summer-phase" Lucké tumor explants.

A herpes-type virus was induced in explants of "summer-phase" Lucké tumor maintained on agar slants at 7.5 C for 13 to 14 weeks.

Zonal centrifuge applied to the purification of Herpesvirus in the Lucké frog kidney tumor.

A series of "winter" and "summer" Lucké kidney tumors of the frog (Rana pipiens) were homogenized and fractionated by differential centrifugation into nuclear, mitochondrial, and mitochondrial supernatant fractions. Winter tumors often contained high concentrations of herpesvirus, whereas no virus was observed in any of the summer tumors. The crude tumor fractions were further purified by rate-zonal sucrose gradient centrifugation in a B-XV zonal rotor. Gradient fractions rich in an enveloped, nucleated form of the herpesvirus from certain winter tumors have induced renal tumors when injected into developing frog embryos. Zonal centrifugation was followed by isopycnic banding of the virus zones for further purification of the different morphological forms of the virus.